The objective of this project was to provide understanding about the mechanisms of sperm differentiation that may be related to induction of sperm morphology mutations in mice and humans. Homozygous PL mice produce a wide range of normal and abnormal sperm. We are studying 1) the comparative morphology of normal and abnormal sperm, 2) ultrastructural mechanisms of differentiation that cause the morphology mutations, and 3) the inheritance of the trait.